The invention relates to intelligent networks and particularly to management of the performance of intelligent network services.
In telecommunications networks intelligence is associated with the ability of accessing stored information, processing it and making decisions on the basis of it. Existing telecommunications networks, such as public switched telephone networks PSTN, are also intelligent to some extent because they are able to process stored information upon call routing, for instance. A typical ‘intelligent’ function in the existing telecommunications networks is conditional call forwarding, in which the call situation has to be analysed and the call forwarded according to the stored service profile of call forwarding. Such intelligent functions have, however, been an inseparable part of the basic network, in which case altering or adding of functions has required updating of the software in each switching centre of the network, for example.
Intelligent network of this kind is exemplified in the ITU-T (the International Telecommunications Union) recommendations of Q-1200 series. The invention and its background art will be described using the CorelNAP terminology of the standard ETS 300 374-1, but the invention can also be applied in intelligent networks implemented in accordance with other intelligent network standards.
An intelligent network IN means a network architecture which is connected to the basic network (e.g. fixed network or mobile communications network) and enables faster, easier and more flexible implementation and control of services. This is achieved by transferring the service control from the switching centre into a separate functional unit of the intelligent network. Thus the services will be independent of the function of the basic network and it is not necessary to alter the structure and the software of the basic network as services are altered or added. In the intelligent network there may be several service providers in addition to the actual network operator.
Standardization of intelligent networks has advanced rapidly during the past years. These standards define a certain functional and hierarchical model for an intelligent network. In this model the call control has been transferred from the switching centre of the basic network into a service control function (SCF) or service control point (SCP) in the intelligent network. The service control function includes all service logic and service-related controlling (e.g. the necessary database and service logic programs (SLP), i.e. computer programs that implement the logical structure of a certain service, i.e. service logic). The service control function may be a mere logic function which can be considered uniform in view of the service control point SSP. Its internal implementation may vary; it may be internally decentralized and the related service logic may be decentralized into different network nodes. The service data may also be decentralized into different network nodes than the service logic. For example, the service control function or point (SCF/SCP) may be internally decentralized so that it provides only an open interface (e.g. COBRA, Common Object Request Broker Architecture) to an external server offered by an external service provider. In that case the SCP and the external server form together the service control function. Intelligent network services are developed, tested and deleted using a specific device called the service creation environment (SCEP). A service management function (SMF) is used for managing the data related to the users and the network in a database, including service-specific data and service programs. A service switching point (SSC) is typically a switching centre, e.g. a switching centre of the basic network, which performs a service switching function (SSF), i.e. identification of the network service and initiation of cooperation with the service control point SCP, but the SSP may also be another kind of network element, e.g. a node (such as H.323 Gatekeeper) which is responsible for establishing a connection in the VoIP protocol (Voice IP). When a call involving an intelligent network service is set up, the service switching point SSP takes care of the connection arrangements. An intelligent network service is produced as follows: an intelligent network service is started when detection points (DP) related to the services and defined by the call state model (BCSM) describing the state of the call control are met, in which case the service switching point SSP asks for instructions from the service control point SCP. In other words, the SSP hands over the control to the SCP and starts to wait for operations from the SCP. In connection with the triggering of an intelligent network service, a service logic program SLP is started in the service control point SCP, the function of the SLP being defined by the instructions the SCP sends to the SSP in each call phase. The SSP interprets the instructions it has received and initiates the call control functions requested in them. Triggering of an intelligent network service means that the intelligent network function is initiated by an impulse generated when a certain identification condition is fulfilled.
The above describes the structure of existing intelligent networks. In this application the intelligent network generally refers to a solution in which a node transmitting a call, a session or packet data contacts the service control function, which gives the node in question instructions affecting the transmission of the call, session or packet data. The communication from the node in question to the service control function is based on the service triggering data possessed by the node. The characteristic features of an intelligent network include triggerings, state models and a protocol giving controls or an API interface between the control function and the network switching node. The call, session or transmission of packet data can be described with a state model which is visible to the control function and consists of phases and detection points which are related to the phases and in which processing can be interrupted to wait for instructions from the control function. Controls and operations may also be methods to be applied to call objects and related event notifications.
An intelligent network may comprise several service control points SCP. All different service control points may provide the same intelligent network services or they may be specialized in certain services. WO 9707637 discloses an intelligent network which comprises several specialized service control points, one of which functions as the router so that the service switching point SSP always first contacts the routing service control point and transmits the service request to a secondary service control point for providing the intelligent network service, or alternatively performs the service itself.
The problem associated with the arrangement described above is that re-routing from the routing service control point causes a delay in the performance of the intelligent network service.